Peel and core the breadfruit.
Cut the breadfruit into chunks or slices, depending on your preference.
In a large pot, bring enough water to a boil to cover the breadfruit chunks.
Add the breadfruit to the boiling water and cook for about 20-30 minutes, or until the breadfruit is tender but not falling apart.
Drain the breadfruit and set aside.
In a bowl, combine the coconut milk, salt, and brown sugar (if using). Mix well.
Place the cooked breadfruit chunks in a large pot or baking dish.
Pour the coconut milk mixture over the breadfruit, ensuring all pieces are well-coated.
If using banana leaves, wrap the breadfruit mixture in the leaves and secure with kitchen twine or toothpicks.
Alternatively, you can cover the baking dish with aluminum foil.
Preheat your oven to 350°F (175°C) if baking, or prepare a steamer if steaming.
If baking, place the wrapped or covered dish in the oven and bake for about 30-40 minutes, or until the coconut milk has thickened slightly and the flavors are well combined.
If steaming, place the wrapped mixture in a steamer basket and steam for about 30-40 minutes.
Allow the ulu to cool slightly before serving.
Enjoy your meal!